Embodiments of the present invention generally relate to optofluidic microscope devices. More specifically, certain embodiments relate to techniques for improving optofluidic microscope (OFM) devices.
Microscopes and other optical microscopy devices are used extensively in all aspects of modern biomedicine and bioscience. Typically, conventional microscopes include an objective lens, a platform for supporting an object, and an eyepiece containing lenses for focusing images. These conventional microscope designs have bulky optics, and have proven to be expensive and difficult to miniaturize.
Some advances in optical microscopy promise to provide more compact systems but have presented significant technical barriers. For example, near field scanning optical microscopes (NSOMs) use a strongly enhanced and tightly confined optical field (near field) at the end of an NSOM probe tip to optically probe a specific location on an object. NSOMs can optically resolve structures with spatial resolutions of ˜50 nm. In addition, NSOM imaging methods are non-destructive and can be used to image objects that are immersed in buffer media. NSOMs are however restricted to detecting light in the near field. Moreover, NSOMs have difficulty performing imaging at high throughput rates (i.e., high numbers of objects being imaged per unit time).
Some microscopy systems have eliminated lenses altogether. FIG. 1(a) is a schematic drawing of a top view of a lensless microscopy system. In this system, an object 10 being imaged is placed directly onto a light detector 11 (e.g., a complementary-symmetry metal-oxide-semiconductor (CMOS) light detector) having a two dimensional array of light detecting elements. The light detector 11 takes a snapshot image 32 of the object 10. The resolution of the snapshot image 102 is generally limited by the size of each light detecting element (e.g., pixel size).
FIG. 1(b) is a schematic drawing of a top view of another lensless microscopy system. The light detector 11 in this system is covered by an aperture layer 14 (e.g., a thin metal layer) with small apertures (holes). The apertures are formed in the aperture layer 14 at locations corresponding to the center of each discrete light detecting element in the light detector. Each light detecting element is generally only sensitive to light transmitted through the aperture above it. Since the apertures are small and relatively widely spaced at a pixel width apart, the light being transmitted through the apertures is a sparse sampling of the light being transmitted through to the aperture layer 14. By placing an object 10 above the aperture layer 14, a sparsely sampled image 34 of the object 10 can be generated. The sparsely sample image 34 may have a better resolution than images generated by the system shown in FIG. 1(a). The resolution of the image is however limited by the pixel size of the light detecting elements of the light detector 11.
FIG. 1(c) is a schematic drawing of a top view of the system of FIG. 1(b) where raster-scanning is employed to take time varying data to generate a filled-in image 36. The filled-in image 36 can be generated by raster-scanning the object 10 over the aperture layer 14 (or raster-scanning the aperture layer 14 over the object 10) and compositing the time varying transmissions of light through the apertures detected by the light detecting elements through the apertures. Since time varying data is used, the resolution of the filled-in image 36 is improved in the x-direction. However, the resolution is limited in the y-direction by the size of each light detecting element (e.g., pixel size).